7.1.9—Whether changes in temperature, concentration

For a given reaction, changing temperature changes the equilibrium constant because it changes the energy balance. Changing concentration or pressure shifts the equilibrium position but leaves K unchanged at that temperature.

Use Le Chatelier for the direction of a shift. For temperature, treat heat as a reactant or product and identify whether the forward reaction is endothermic or exothermic.

For N₂ + 3H₂ ⇌ 2NH₃ + heat, raising temperature shifts left and lowers K; adding nitrogen shifts right but does not change K.

A catalyst changes the rates of both directions, not K or the final equilibrium composition. Pressure changes K only indirectly if temperature also changes.